Get subfield 'a',
remove non-digits.
If result is exactly 8 digits,
substr(result,
0,
2) >=70 or =00 or error.
New field a = ' result ' If result is exactly 10 digits,
substr(result,
0,
4) >=2001 and <= 2010 (will change as year changes) or error.
New field a = ' result' Compare new field a with existing field a and report only those that differ.